Lithofacies variation and unconformities in the metalliferous rocks underlying the Permian Kupferschiefer of the Stockheim Basin, Federal Republic of Germany

Two separate depositional facies of the Lower Permian and upper Carboniferous clastic and volcanoclastic sediments of the Stockheim basin show distinctive controls of the deposition of selected chemical elements. An older stage represents a caldera-playa environment in which there are signs of incipient rifting, lava extrusion, deposition of pyroclastic and epiclastic fans shed into a subsiding basin, and moat-fill deposition. U was syngenetically (diagenetically) concentrated in the distal fan facies in which organic matter was abundant. U, Sb, Au, Ag, and Se derived from initial volcanism occur in the lowermost gray beds. Mn-bearing carbonates occur in moat-fill deposits and show a pronounced zoning relative to feeder channels of hydrothermal fluids (T